The scope of this project has been expanded to include the advanced sleep phase syndrome (ASPS). The investigators have concentrated on this disorder over the past year. Five pedigrees have been identified with ASPS and three have been intensely studies utilizing the GCRC and the sleep laboratory. Circadian phase was determined using plasma melatonin and body core temperature measurements. Preliminary data has indicated linkage to defined loci for two of the three pedigrees studied. The candidate gene approach is now being employed with genes known to be located at the chromosomal locations to which linkage has been established. The families ascertained by Dr. Ptaeck afford a unique opportunity to understand the genetics and physiology of the monogenic human sleep disorder. Other disorders under study by Dr. Ptacek and his group (which includes Dr. Kathryn Swoboda, the GCRC clinical associate physical) includes spinocerebellar ataxia, periodic paralysis, cerebral cavernous angiomata and paroxysmal motion disorders.